Liquid nicotine formulation

ABSTRACT

A liquid nicotine formulation for an aerosol-generating system is provided, the liquid nicotine formulation including: one or more water-miscible solvents; one or more water-immiscible solvents having a water solubility at 20° C. of less than or equal to about 100 mg/ml; and one or more water-soluble organic acids, the liquid nicotine formulation having a water-immiscible solvent content of greater than or equal to about 2 percent by weight. A cartridge for an aerosol-generating system, and an aerosol-generating system, are also provided.

The invention relates to a liquid nicotine formulation for use in anaerosol-generating system. The invention also relates to a cartridge foran aerosol-generating system comprising the liquid nicotine formulationand an aerosol-generating system comprising the liquid nicotineformulation and an atomiser configured to generate an aerosol from theliquid nicotine formulation.

Aerosol-generating systems for delivering nicotine to a user thatcomprise an atomiser configured to generate an inhalable aerosol from aliquid nicotine formulation are known. Some known aerosol-generatingsystems comprise a thermal atomiser such as an electric heater that isconfigured to heat and vaporise the liquid nicotine formulation togenerate an aerosol. Other known aerosol-generating systems comprise anon-thermal atomiser that is configured to generate an aerosol from theliquid nicotine formulation using, for example, impinging jet,ultrasonic or vibrating mesh technologies.

In such aerosol-generating systems, efficient pulmonary delivery of theinhalable aerosol generated from the liquid nicotine formulation isbelieved to be an important criteria for user palatability andsatisfaction. Typical liquid nicotine formulations for use inaerosol-generating systems comprise glycerine, propylene glycol andwater as solvents.

It would be desirable to provide a liquid nicotine formulation for usein an aerosol-generating system that that enables generation of anaerosol providing improved nicotine satisfaction to a user compared tosuch typical liquid nicotine formulations. In particular, it would bedesirable to provide a liquid nicotine formulation for use in anaerosol-generating system that enables generation of an aerosolproviding similar nicotine satisfaction to a user as tobacco smokegenerated from combusting a conventional cigarette.

According to a first aspect of the invention there is provided a liquidnicotine formulation for use in an aerosol-generating system, the liquidnicotine formulation comprising: one or more water-miscible solvents;one or more water-immiscible solvents having a water solubility at 20°C. of less than or equal to about 100 mg/ml; and one or morewater-soluble organic acids.

According to the first aspect of the invention there is also provided acartridge for use in an aerosol-generating system, the cartridgecontaining a liquid nicotine formulation comprising: one or morewater-miscible solvents; one or more water-immiscible solvents having awater solubility at 20° C. of less than or equal to about 100 mg/ml; andone or more water-soluble organic acids.

According to the first aspect of the invention there is further providedan aerosol-generating system comprising: a liquid nicotine formulationcomprising: one or more water-miscible solvents; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids; and an atomiser configured to generate an aerosol from the liquidnicotine formulation.

According to a second aspect of the invention there is provided a liquidnicotine formulation for use in an aerosol-generating system, the liquidnicotine formulation comprising: one or more water-miscible solvents;one or more water-immiscible solvents having a partition coefficient(log P) at 20° C. of greater than or equal to about 0.05; and one ormore water-soluble organic acids.

According to the second aspect of the invention there is also provided acartridge for use in an aerosol-generating system, the cartridgecontaining a liquid nicotine formulation comprising: one or morewater-miscible solvents; one or more water-immiscible solvents having apartition coefficient (log P) at 20° C. of greater than or equal toabout 0.05; and one or more water-soluble organic acids.

According to the second aspect of the invention there is furtherprovided an aerosol-generating system comprising: a liquid nicotineformulation comprising: one or more water-miscible solvents; one or morewater-immiscible solvents having a partition coefficient (log P) at 20°C. of greater than or equal to about 0.05; and one or more water-solubleorganic acids; and an atomiser configured to generate an aerosol fromthe liquid nicotine formulation.

As used herein with reference to the invention, the term “liquidnicotine formulation” describes a liquid formulation comprisingnicotine.

As used herein with reference to the invention, the term “nicotine”describes nicotine, nicotine base or a nicotine salt. In embodiments inwhich the liquid nicotine formulation comprises a nicotine base or anicotine salt, the amounts of nicotine recited herein are the amount offree base nicotine or amount of protonated nicotine, respectively.

As used herein with reference to the invention, the term “water-misciblesolvent” describes a compound other than water or an organic acid thatis liquid at 20° C. and mixes with water in all proportions to form ahomogenous solution.

As used herein with reference to the invention, the term “water-solubleorganic acid” describes an organic acid having a water solubility at 20°C. of greater than or equal to about 500 mg/ml.

Unless stated otherwise, water solubility values recited herein are thewater solubility measured based on the preliminary test of OECD (1995),Test No. 105: Water Solubility, OECD Guidelines for the Testing ofChemicals, Section 1, OECD Publishing, Paris,https://doi.org/10.1787/9789264069589-en. In a stepwise procedure,increasing volumes of distilled water are added at 20° C. to 0.1 g ofthe sample (solid substances must be pulverized) in a 10 mlglass-stoppered measuring cylinder. However, when the substance is anacid, the sample is added to the distilled water in the first step.After each addition of an amount of water, the mixture is shaken for 10minutes and is visually checked for any undissolved parts of the sample.If, after addition of 10 ml of water, the sample or parts of it remainundissolved, the experiment is continued in a 100 ml measuring cylinder.The approximate solubility is given in Table 1 below under that volumeof water in which complete dissolution of the sample occurs.

When the solubility is low, a long time may be required to dissolve asubstance and at least 24 hours should be allowed. If, after 24 hours,the substance is still not dissolved, the measuring cylinder is placedfor at 40° C. in an ultrasound bath for 15 minutes and another 24 hoursallowed (up to a maximum of 96 hours). If the substance is still notdissolved, the solubility is considered to be below the limit value ornot soluble.

TABLE 1 ml of water in which 0.1 0.5 1 2 10 100 >100 0.1 g of sample issoluble Approximate solubility (mg/ml) >1000 1000 to 200 200 to 100 100to 50 50 to 10 10 to 1 <1

As used herein with reference to the first aspect of the invention, theterm “water-immiscible solvent” describes a compound that is liquid at20° C. and has a water solubility at 20° C. of less than or equal toabout 100 mg/ml.

As used herein with reference to the second aspect of the invention, theterm “water-immiscible solvent” describes a compound that is liquid at20° C. and has a partition coefficient (log P) at 20° C. of greater thanor equal to about 0.05.

Unless stated otherwise, partition coefficient (log P) values recitedherein are the octanol/water partition coefficient (log P_(OW)) measuredin accordance with: OECD (1995), Test No. 107: Partition Coefficient(n-octanol/water): Shake Flask Method, OECD Guidelines for the Testingof Chemicals, Section 1, OECD Publishing, Paris,https://doi.org/10.1787/9789264069626-en (for values in the range logP_(OW) between −2 and 4); OECD (2004), Test No. 117: PartitionCoefficient (n-octanol/water), HPLC Method, OECD Guidelines for theTesting of Chemicals, Section 1, OECD Publishing, Paris,https://doi.org/10.1787/9789264069824-en (for values in the range logP_(OW) between 0 and 6); and OECD (2006), Test No. 123: PartitionCoefficient (1-Octanol/Water): Slow-Stirring Method, OECD Guidelines forthe Testing of Chemicals, Section 1, OECD Publishing, Paris,https://doi.org/10.1787/9789264015845-en (for values in the range logP_(OW) up to 8.2).

Inclusion of a combination of one or more water-miscible solvents, oneor more water-immiscible solvents and one or more water-soluble organicacids in the liquid nicotine formulation according to the inventionadvantageously enables generation of an inhalable aerosol providingimproved nicotine satisfaction to a user compared to typical liquidnicotine formulations. In particular, as discussed further below,inclusion of a combination of one or more water-miscible solvents, oneor more water-immiscible solvents and one or more water-soluble organicacids in the liquid nicotine formulation according to the inventionadvantageously enables generation of an inhalable aerosol havingimproved nicotine retention properties compared to typical liquidnicotine formulations.

Tobacco smoke generated by combustion of conventional cigarettescomprises thousands of different smoke components. It has surprisinglybeen found that inclusion of a combination of one or more water-misciblesolvents, one or more water-immiscible solvents and one or morewater-soluble organic acids in the liquid nicotine formulation accordingto the invention advantageously enables generation of an inhalableaerosol having nicotine retention properties similar to those of tobaccosmoke generated from combustion of a conventional cigarette.

Unless stated otherwise, percentages by weight of components of theliquid nicotine formulation recited herein are based on the total weightof the liquid nicotine formulation.

The liquid nicotine formulation may comprise natural nicotine orsynthetic nicotine.

The liquid nicotine formulation may have a nicotine content of greaterthan or equal to about 0.5 percent by weight.

Preferably, the liquid nicotine formulation has a nicotine content ofgreater than or equal to about 1 percent by weight. More preferably, theliquid nicotine formulation has a nicotine content of greater than orequal to about 1.5 percent by weight.

The liquid nicotine formulation may have a nicotine content of less thanor equal to about 10 percent by weight. The liquid nicotine formulationmay have a nicotine content of less than or equal to about 8 percent byweight.

Preferably, the liquid nicotine formulation has a nicotine content ofless than or equal to about 5 percent by weight. More preferably, theliquid nicotine formulation has a nicotine content of less than or equalto about 3 percent by weight.

The liquid nicotine formulation may have a nicotine content of betweenabout 0.5 percent by weight and about 10 percent by weight. For example,the liquid nicotine formulation may have a nicotine content of betweenabout 0.5 percent by weight and about 8 percent by weight, between about0.5 percent by weight and about 5 percent by weight or between about 0.5percent by weight and about 3 percent by weight.

Preferably, the liquid nicotine formulation has a nicotine content ofbetween about 1 percent by weight and about 10 percent by weight. Forexample, the liquid nicotine formulation may have a nicotine content ofbetween about 1 percent by weight and about 8 percent by weight, betweenabout 1 percent by weight and about 5 percent by weight or between about1 percent by weight and about 3 percent by weight.

More preferably, the liquid nicotine formulation has a nicotine contentof between about 1.5 percent by weight and about 10 percent by weight.For example, the liquid nicotine formulation may have a nicotine contentof between about 1.5 percent by weight and about 8 percent by weight,between about 1.5 percent by weight and about 5 percent by weight orbetween about 1.5 percent by weight and about 3 percent by weight.

The liquid nicotine formulation comprises one or more water-misciblesolvents. The one or more water-miscible solvents may advantageouslyhelp to dissolve and stabilise polar components and ionic components ofthe liquid nicotine formulation.

Preferably, the liquid nicotine formulation has a water-miscible solventcontent of greater than or equal to about 5 percent by weight. Morepreferably, the liquid nicotine formulation has a water-miscible solventcontent of greater than or equal to about 10 percent by weight. Forexample, the liquid nicotine formulation may have a water-misciblesolvent content of greater than or equal to about 15 percent by weight,greater than or equal to about 20 percent by weight or greater than orequal to about 25 percent by weight.

The liquid nicotine formulation may have a water-miscible solventcontent of less than or equal to about 80 percent by weight or less thanor equal to about 75 percent by weight.

Preferably, the liquid nicotine formulation has a water-miscible solventcontent of less than or equal to about 70 percent by weight. Morepreferably, the liquid nicotine formulation has a water-miscible solventcontent of less than or equal to about 60 percent by weight. Forexample, the liquid nicotine formulation may have a water-misciblesolvent content of less than or equal to about 50 percent by weight orless than or equal to about 40 percent by weight.

Preferably, the liquid nicotine formulation has a water-miscible solventcontent of between about 5 percent by weight and about 70 percent byweight. For example, the liquid nicotine formulation may have awater-miscible solvent content of between about 5 percent by weight andabout 60 percent by weight, between about 5 percent by weight and about50 percent by weight or between about 5 percent by weight and about 40percent by weight.

More preferably, the liquid nicotine formulation has a water-misciblesolvent content of between about 10 percent by weight and about 70percent by weight. For example, the liquid nicotine formulation may havea water-miscible solvent content of between about 10 percent by weightand about 60 percent by weight, between about 10 percent by weight andabout 50 percent by weight or between about 10 percent by weight andabout 40 percent by weight.

The liquid nicotine formulation may have a water-miscible solventcontent of between about 15 percent by weight and about 70 percent byweight, between about 15 percent by weight and about 60 percent byweight, between about 15 percent by weight and about 50 percent byweight or between about 15 percent by weight and about 40 percent byweight.

The liquid nicotine formulation may have a water-miscible solventcontent of between about 20 percent by weight and about 70 percent byweight, between about 20 percent by weight and about 60 percent byweight, between about 20 percent by weight and about 50 percent byweight or between about 20 percent by weight and about 40 percent byweight.

The liquid nicotine formulation may have a water-miscible solventcontent of between about 25 percent by weight and about 70 percent byweight, between about 25 percent by weight and about 60 percent byweight, between about 25 percent by weight and about 50 percent byweight or between about 25 percent by weight and about 40 percent byweight.

Preferably, the one or more water-miscible solvents are one or morewater-miscible polyhydric alcohols.

As used herein with reference to the invention, the term “water-misciblepolyhydric alcohol” describes a polyhydric alcohol that is liquid at 20°C. and mixes with water in all proportions to form a homogenoussolution.

According to a preferred embodiment of the first aspect of the inventionthere is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:one or more water-miscible polyhydric alcohols; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a preferred embodiment of the first aspect of the inventionthere is also provided a cartridge for use in an aerosol-generatingsystem, the cartridge containing a liquid nicotine formulationcomprising: one or more water-miscible polyhydric alcohols; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a preferred embodiment of the first aspect of the inventionthere is further provided an aerosol-generating system comprising: aliquid nicotine formulation comprising one or more water-misciblepolyhydric alcohols; one or more water-immiscible solvents having awater solubility at 20° C. of less than or equal to about 100 mg/ml; andone or more water-soluble organic acids; and an atomiser configured togenerate an aerosol from the liquid nicotine formulation.

According to a preferred embodiment of the second aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:one or more water-miscible polyhydric alcohols; one or morewater-immiscible solvents having a partition coefficient (log P) at 20°C. of greater than or equal to about 0.05; and one or more water-solubleorganic acids.

According to a preferred embodiment of the second aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: one or more water-miscible polyhydric alcohols;one or more water-immiscible solvents having a partition coefficient(log P) at 20° C. of greater than or equal to about 0.05; and one ormore water-soluble organic acids.

According to a preferred embodiment of the second aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: one or morewater-miscible polyhydric alcohols; one or more water-immisciblesolvents having a partition coefficient (log P) at 20° C. of greaterthan or equal to about 0.05; and one or more water-soluble organicacids; and an atomiser configured to generate an aerosol from the liquidnicotine formulation.

Preferably, the liquid nicotine formulation has a water-misciblepolyhydric alcohol content of greater than or equal to about 5 percentby weight. More preferably, the liquid nicotine formulation has awater-miscible polyhydric alcohol content of greater than or equal toabout 10 percent by weight. For example, the liquid nicotine formulationmay have a water-miscible polyhydric alcohol content of greater than orequal to about 15 percent by weight, greater than or equal to about 20percent by weight or greater than or equal to about 25 percent byweight.

The liquid nicotine formulation may have a water-miscible polyhydricalcohol content of less than or equal to about 80 percent by weight orless than or equal to about 75 percent by weight.

Preferably, the liquid nicotine formulation has a water-misciblepolyhydric alcohol content of less than or equal to about 70 percent byweight. More preferably, the liquid nicotine formulation has awater-miscible polyhydric alcohol content of less than or equal to about60 percent by weight. For example, the liquid nicotine formulation mayhave a water-miscible polyhydric alcohol content of less than or equalto about 50 percent by weight or less than or equal to about 40 percentby weight.

Preferably, the liquid nicotine formulation has a water-misciblepolyhydric alcohol content of between about 5 percent by weight andabout 70 percent by weight. For example, the liquid nicotine formulationmay have a water-miscible polyhydric alcohol content of between about 5percent by weight and about 60 percent by weight, between about 5percent by weight and about 50 percent by weight or between about 5percent by weight and about 40 percent by weight.

More preferably, the liquid nicotine formulation has a water-misciblepolyhydric alcohol content of between about 10 percent by weight andabout 70 percent by weight. For example, the liquid nicotine formulationmay have a water-miscible polyhydric alcohol content of between about 10percent by weight and about 60 percent by weight, between about 10percent by weight and about 50 percent by weight or between about 10percent by weight and about 40 percent by weight.

The liquid nicotine formulation may have a water-miscible polyhydricalcohol content of between about 15 percent by weight and about 70percent by weight, between about 15 percent by weight and about 60percent by weight, between about 15 percent by weight and about 50percent by weight or between about 15 percent by weight and about 40percent by weight.

The liquid nicotine formulation may have a water-miscible polyhydricalcohol content of between about 20 percent by weight and about 70percent by weight, between about 20 percent by weight and about 60percent by weight, between about 20 percent by weight and about 50percent by weight or between about 20 percent by weight and about 40percent by weight.

The liquid nicotine formulation may have a water-miscible polyhydricalcohol content of between about 25 percent by weight and about 70percent by weight, between about 25 percent by weight and about 60percent by weight, between about 25 percent by weight and about 50percent by weight or between about 25 percent by weight and about 40percent by weight.

Preferably, the one or more water-miscible polyhydric alcohols areselected from the group consisting of 1,3-butanediol, glycerine,propylene glycol, and triethylene glycol.

More preferably, the one or more water-miscible polyhydric alcohols areselected from the group consisting of glycerine and propylene glycol.

Most preferably, the one or more water-miscible polyhydric alcohols areselected from the group consisting of vegetable glycerine and propyleneglycol.

According to a preferred embodiment of the first aspect of the inventionthere is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:one or more water-miscible polyhydric alcohols selected from the groupconsisting of glycerine and propylene glycol; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a preferred embodiment of the first aspect of the inventionthere is also provided a cartridge for use in an aerosol-generatingsystem, the cartridge containing a liquid nicotine formulationcomprising: one or more water-miscible polyhydric alcohols selected fromthe group consisting of glycerine and propylene glycol; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a preferred embodiment of the first aspect of the inventionthere is further provided an aerosol-generating system comprising: aliquid nicotine formulation comprising one or more water-misciblepolyhydric alcohols selected from the group consisting of glycerine andpropylene glycol; one or more water-immiscible solvents having a watersolubility at 20° C. of less than or equal to about 100 mg/ml; and oneor more water-soluble organic acids; and an atomiser configured togenerate an aerosol from the liquid nicotine formulation.

According to a preferred embodiment of the second aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:one or more water-miscible polyhydric alcohols selected from the groupconsisting of glycerine and propylene glycol; one or morewater-immiscible solvents having a partition coefficient (log P) at 20°C. of greater than or equal to about 0.05; and one or more water-solubleorganic acids.

According to a preferred embodiment of the second aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: one or more water-miscible polyhydric alcoholsselected from the group consisting of glycerine and propylene glycol;one or more water-immiscible solvents having a partition coefficient(log P) at 20° C. of greater than or equal to about 0.05; and one ormore water-soluble organic acids.

According to a preferred embodiment of the second aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: one or morewater-miscible polyhydric alcohols selected from the group consisting ofglycerine and propylene glycol; one or more water-immiscible solventshaving a partition coefficient (log P) at 20° C. of greater than orequal to about 0.05; and one or more water-soluble organic acids; and anatomiser configured to generate an aerosol from the liquid nicotineformulation.

Preferably, the liquid nicotine formulation has a combined glycerine andpropylene glycol content of greater than or equal to about 5 percent byweight. More preferably, the liquid nicotine formulation has a combinedglycerine and propylene glycol content of greater than or equal to about10 percent by weight. For example, the liquid nicotine formulation mayhave a combined glycerine and propylene glycol content of greater thanor equal to about 15 percent by weight, greater than or equal to about20 percent by weight or greater than or equal to about 25 percent byweight.

The liquid nicotine formulation may have a combined glycerine andpropylene glycol content of less than or equal to about 80 percent byweight or less than or equal to about 75 percent by weight.

Preferably, the liquid nicotine formulation has a combined glycerine andpropylene glycol content of less than or equal to about 70 percent byweight. More preferably, the liquid nicotine formulation has a combinedglycerine and propylene glycol content of less than or equal to about 60percent by weight. For example, the liquid nicotine formulation may havea combined glycerine and propylene glycol content of less than or equalto about 50 percent by weight or less than or equal to about 40 percentby weight.

Preferably, the liquid nicotine formulation has a combined glycerine andpropylene glycol content of between about 5 percent by weight and about70 percent by weight. For example, the liquid nicotine formulation mayhave a combined glycerine and propylene glycol content of between about5 percent by weight and about 60 percent by weight, between about 5percent by weight and about 50 percent by weight or between about 5percent by weight and about 40 percent by weight.

More preferably, the liquid nicotine formulation has a combinedglycerine and propylene glycol content of between about 10 percent byweight and about 70 percent by weight. For example, the liquid nicotineformulation may have a combined glycerine and propylene glycol contentof between about 10 percent by weight and about 60 percent by weight,between about 10 percent by weight and about 50 percent by weight orbetween about 10 percent by weight and about 40 percent by weight.

The liquid nicotine formulation may have a combined glycerine andpropylene glycol content of between about 15 percent by weight and about70 percent by weight, between about 15 percent by weight and about 60percent by weight, between about 15 percent by weight and about 50percent by weight or between about 15 percent by weight and about 40percent by weight.

The liquid nicotine formulation may have a combined glycerine andpropylene glycol content of between about 20 percent by weight and about70 percent by weight, between about 20 percent by weight and about 60percent by weight, between about 20 percent by weight and about 50percent by weight or between about 20 percent by weight and about 40percent by weight.

The liquid nicotine formulation may have a combined glycerine andpropylene glycol content of between about 25 percent by weight and about70 percent by weight, between about 25 percent by weight and about 60percent by weight, between about 25 percent by weight and about 50percent by weight or between about 25 percent by weight and about 40percent by weight.

Preferably, the liquid nicotine formulation has a glycerine content ofgreater than or equal to about 5 percent by weight.

More preferably, the liquid nicotine formulation has a glycerine contentof greater than or equal to about 6 percent by weight. For example, theliquid nicotine formulation may have a glycerine content of greater thanor equal to about 7 percent by weight or greater than or equal to about8 percent by weight.

The liquid nicotine formulation may have a glycerine content of lessthan or equal to about 80 percent by weight or less than or equal toabout 75 percent by weight.

Preferably, the liquid nicotine formulation has a glycerine content ofless than or equal to about 70 percent by weight. More preferably, theliquid nicotine formulation has a glycerine content of less than orequal to about 60 percent by weight. For example, the liquid nicotineformulation may have a glycerine content of less than or equal to about50 percent by weight or less than or equal to about 40 percent byweight.

Preferably, the liquid nicotine formulation has a glycerine content ofbetween about 5 percent by weight and about 70 percent by weight. Forexample, the liquid nicotine formulation may have a glycerine content ofbetween about 5 percent by weight and about 60 percent by weight,between about 5 percent by weight and about 50 percent by weight orbetween about 5 percent by weight and about 40 percent by weight.

More preferably, the liquid nicotine formulation has a glycerine contentof between about 6 percent by weight and about 70 percent by weight. Forexample, the liquid nicotine formulation may have a glycerine content ofbetween about 6 percent by weight and about 60 percent by weight,between about 6 percent by weight and about 50 percent by weight orbetween about 6 percent by weight and about 40 percent by weight.

The liquid nicotine formulation may have a glycerine content of betweenabout 7 percent by weight and about 70 percent by weight, between about7 percent by weight and about 60 percent by weight, between about 7percent by weight and about 50 percent by weight or between about 7percent by weight and about 40 percent by weight.

The liquid nicotine formulation may have a glycerine content of betweenabout 8 percent by weight and about 70 percent by weight, between about8 percent by weight and about 60 percent by weight, between about 8percent by weight and about 50 percent by weight or between about 8percent by weight and about 40 percent by weight.

Preferably, the liquid nicotine formulation comprises water and one ormore water-miscible solvents.

According to a preferred embodiment of the first aspect of the inventionthere is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:water; one or more water-miscible solvents; one or more water-immisciblesolvents having a water solubility at 20° C. of less than or equal toabout 100 mg/ml; and one or more water-soluble organic acids.

According to a preferred embodiment of the first aspect of the inventionthere is also provided a cartridge for use in an aerosol-generatingsystem, the cartridge containing a liquid nicotine formulationcomprising: water; one or more water-miscible solvents; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a preferred embodiment of the first aspect of the inventionthere is further provided an aerosol-generating system comprising: aliquid nicotine formulation comprising: water; one or morewater-miscible solvents; one or more water-immiscible solvents having awater solubility at 20° C. of less than or equal to about 100 mg/ml; andone or more water-soluble organic acids; and an atomiser configured togenerate an aerosol from the liquid nicotine formulation.

According to a preferred embodiment of the second aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:water; one or more water-miscible solvents; one or more water-immisciblesolvents having a partition coefficient (log P) at 20° C. of greaterthan or equal to about 0.05; and one or more water-soluble organicacids.

According to a preferred embodiment of the second aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: water; one or more water-miscible solvents; oneor more water-immiscible solvents having a partition coefficient (log P)at 20° C. of greater than or equal to about 0.05; and one or morewater-soluble organic acids.

According to a preferred embodiment of the second aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: water; one or morewater-miscible solvents; one or more water-immiscible solvents having apartition coefficient (log P) at 20° C. of greater than or equal toabout 0.05; and one or more water-soluble organic acids; and an atomiserconfigured to generate an aerosol from the liquid nicotine formulation.

In combination the water and one or more water-miscible solvents mayadvantageously help to dissolve and stabilise polar components and ioniccomponents of the liquid nicotine formulation.

The liquid nicotine formulation may have a water content of greater thanor equal to about 5 percent by weight.

Preferably, the liquid nicotine formulation has a water content ofgreater than or equal to about 10 percent by weight. More preferably,the liquid nicotine formulation has a water-content of greater than orequal to about 15 percent by weight. Most preferably, the liquidnicotine formulation has a water content of greater than or equal toabout 20 percent by weight. For example, the liquid nicotine formulationmay have a water content of greater than or equal to about 25 percent byweight, greater than or equal to about 30 percent by weight or greaterthan or equal to about 35 percent by weight.

Preferably, the liquid nicotine formulation has a water content of lessthan or equal to about 90 percent by weight. More preferably, the liquidnicotine formulation has a water content of less than or equal to about85 percent by weight. For example, the liquid nicotine formulation mayhave a water content of less than or equal to about 80 percent byweight, less than or equal to about 75 percent by weight, less than orequal to about 70 percent by weight or less than or equal to about 65percent by weight.

The liquid nicotine formulation may have a water content of betweenabout 5 percent by weight and about 90 percent by weight. For example,the liquid nicotine formulation may have a water content of betweenabout 5 percent by weight and about 85 percent by weight, between about5 percent by weight and about 80 percent by weight, between about 5percent by weight and about 75 percent by weight, between about 5percent by weight and about 70 percent by weight or between about 5percent by weight and about 65 percent by weight.

Preferably, the liquid nicotine formulation has a water content ofbetween about 10 percent by weight and about 90 percent by weight. Forexample, the liquid nicotine formulation may have a water content ofbetween about 10 percent by weight and about 85 percent by weight,between about 10 percent by weight and about 80 percent by weight,between about 10 percent by weight and about 75 percent by weight,between about 10 percent by weight and about 70 percent by weight orbetween about 10 percent by weight and about 65 percent by weight.

More preferably, the liquid nicotine formulation has a water content ofbetween about 15 percent by weight and about 90 percent by weight. Forexample, the liquid nicotine formulation may have a water content ofbetween about 15 percent by weight and about 85 percent by weight,between about 15 percent by weight and about 80 percent by weight,between about 15 percent by weight and about 75 percent by weight,between about 15 percent by weight and about 70 percent by weight,between about 15 percent by weight and about 65 percent by weight.

Most preferably, the liquid nicotine formulation has a water content ofbetween about 20 percent by weight and about 90 percent by weight. Forexample, the liquid nicotine formulation may have a water content ofbetween about 20 percent by weight and about 85 percent by weight,between about 20 percent by weight and about 80 percent by weight,between about 20 percent by weight and about 75 percent by weight,between about 20 percent by weight and about 70 percent by weight orbetween about 20 percent by weight and about 65 percent by weight.

The liquid nicotine formulation may have a water content of betweenabout 25 percent by weight and about 90 percent by weight. For example,the liquid nicotine formulation may have a water content of betweenabout 25 percent by weight and about 85 percent by weight, between about25 percent by weight and about 80 percent by weight, between about 25percent by weight and about 75 percent by weight, between about 25percent by weight and about 70 percent by weight or between about 25percent by weight and about 65 percent by weight.

The liquid nicotine formulation may have a water content of betweenabout 30 percent by weight and about 90 percent by weight. For example,the liquid nicotine formulation may have a water content of betweenabout 30 percent by weight and about 85 percent by weight, between about30 percent by weight and about 80 percent by weight, between about 30percent by weight and about 75 percent by weight, between about 30percent by weight and about 70 percent by weight or between about 30percent by weight and about 65 percent by weight.

The liquid nicotine formulation comprises may have a water content ofbetween about 35 percent by weight and about 90 percent by weight. Forexample, the liquid nicotine formulation may have a water content ofbetween about 35 percent by weight and about 85 percent by weight,between about 35 percent by weight and about 80 percent by weight,between about 35 percent by weight and about 75 percent by weight,between about 35 percent by weight and about 70 percent by weight orbetween about 35 percent by weight and about 65 percent by weight.

The liquid nicotine formulation may have a combined water andwater-miscible solvent content of greater than or equal to about 50percent by weight, greater than or equal to about 55 percent by weight,greater than or equal to about 60 percent by weight, greater than orequal to about 65 percent by weight or greater than or equal to about 70percent by weight.

Preferably, the liquid nicotine formulation has a combined water andwater-miscible solvent content of greater than or equal to about 75percent by weight. More preferably, the liquid nicotine formulation hasa combined water and water-miscible solvent content of greater than orequal to 80 percent by weight. For example, the liquid nicotineformulation may have a combined water and water-miscible solvent contentof greater than or equal to about 85 percent by weight.

More preferably, the liquid nicotine formulation comprises water and oneor more water-miscible polyhydric alcohols.

According to a more preferred embodiment of the first aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:water; one or more water-miscible polyhydric alcohols; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a more preferred embodiment of the first aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: water; one or more water-miscible polyhydricalcohols; one or more water-immiscible solvents having a watersolubility at 20° C. of less than or equal to about 100 mg/ml; and oneor more water-soluble organic acids.

According to a more preferred embodiment of the first aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: water; one or morewater-miscible polyhydric alcohols; one or more water-immisciblesolvents having a water solubility at 20° C. of less than or equal toabout 100 mg/ml; and one or more water-soluble organic acids; and anatomiser configured to generate an aerosol from the liquid nicotineformulation.

According to a more preferred embodiment of the second aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:water; one or more water-miscible polyhydric alcohols; one or morewater-immiscible solvents having a partition coefficient (log P) at 20°C. of greater than or equal to about 0.05; and one or more water-solubleorganic acids.

According to a more preferred embodiment of the second aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: water; one or more water-miscible polyhydricalcohols; one or more water-immiscible solvents having a partitioncoefficient (log P) at 20° C. of greater than or equal to about 0.05;and one or more water-soluble organic acids.

According to a more preferred embodiment of the second aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: water; one or morewater-miscible polyhydric alcohols; one or more water-immisciblesolvents having a partition coefficient (log P) at 20° C. of greaterthan or equal to about 0.05; and one or more water-soluble organicacids; and an atomiser configured to generate an aerosol from the liquidnicotine formulation.

In embodiments in which the liquid nicotine formulation comprises waterand one or more water-miscible polyhydric alcohols, the liquid nicotineformulation may have a combined water and water-miscible polyhydricalcohol content of greater than or equal to about 50 percent by weight,greater than or equal to about 55 percent by weight, greater than orequal to about 60 percent by weight, greater than or equal to about 65percent by weight or greater than or equal to about 70 percent byweight.

In embodiments in which the liquid nicotine formulation comprises waterand one or more water-miscible polyhydric alcohols, preferably theliquid nicotine formulation has a combined water and water-misciblepolyhydric alcohol content of greater than or equal to about 75 percentby weight. More preferably, the liquid nicotine formulation has acombined water and water-miscible polyhydric alcohol content of greaterthan or equal to 80 percent by weight. For example, the liquid nicotineformulation may have a combined water and water-miscible polyhydricalcohol content of greater than or equal to about 85 percent by weight.

Most preferably, the liquid nicotine formulation comprises water and oneor more water-miscible polyhydric alcohols selected from the groupconsisting of glycerine and propylene glycol.

According to a more preferred embodiment of the first aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:water; one or more water-miscible polyhydric alcohols selected from thegroup consisting of glycerine and propylene glycol; one or morewater-immiscible solvents having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml; and one or more water-soluble organicacids.

According to a more preferred embodiment of the first aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: water; one or more water-miscible polyhydricalcohols selected from the group consisting of glycerine and propyleneglycol; one or more water-immiscible solvents having a water solubilityat 20° C. of less than or equal to about 100 mg/ml; and one or morewater-soluble organic acids.

According to a more preferred embodiment of the first aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: water; one or morewater-miscible polyhydric alcohols selected from the group consisting ofglycerine and propylene glycol; one or more water-immiscible solventshaving a water solubility at 20° C. of less than or equal to about 100mg/ml; and one or more water-soluble organic acids; and an atomiserconfigured to generate an aerosol from the liquid nicotine formulation.

According to a more preferred embodiment of the second aspect of theinvention there is provided a liquid nicotine formulation for use in anaerosol-generating system, the liquid nicotine formulation comprising:water; one or more water-miscible polyhydric alcohols selected from thegroup consisting of glycerine and propylene glycol; one or morewater-immiscible solvents having a partition coefficient (log P) at 20°C. of greater than or equal to about 0.05; and one or more water-solubleorganic acids.

According to a more preferred embodiment of the second aspect of theinvention there is also provided a cartridge for use in anaerosol-generating system, the cartridge containing a liquid nicotineformulation comprising: water; one or more water-miscible polyhydricalcohols selected from the group consisting of glycerine and propyleneglycol; one or more water-immiscible solvents having a partitioncoefficient (log P) at 20° C. of greater than or equal to about 0.05;and one or more water-soluble organic acids.

According to a more preferred embodiment of the second aspect of theinvention there is further provided an aerosol-generating systemcomprising: a liquid nicotine formulation comprising: water; one or morewater-miscible polyhydric alcohols selected from the group consisting ofglycerine and propylene glycol; one or more water-immiscible solventshaving a partition coefficient (log P) at 20° C. of greater than orequal to about 0.05; and one or more water-soluble organic acids; and anatomiser configured to generate an aerosol from the liquid nicotineformulation.

In embodiments in which the liquid nicotine formulation comprises waterand one or more water-miscible polyhydric alcohols selected from thegroup consisting of glycerine and propylene glycol, the liquid nicotineformulation may have a combined water, glycerine and propylene glycolcontent of greater than or equal to about 50 percent by weight, greaterthan or equal to about 55 percent by weight, greater than or equal toabout 60 percent by weight, greater than or equal to about 65 percent byweight or greater than or equal to about 70 percent by weight.

In embodiments in which the liquid nicotine formulation comprises waterand one or more water-miscible polyhydric alcohols selected from thegroup consisting of glycerine and propylene glycol, preferably theliquid nicotine formulation has a combined water, glycerine andpropylene glycol content of greater than or equal to about 75 percent byweight. More preferably, the liquid nicotine formulation has a combinedwater, glycerine and propylene glycol content of greater than or equalto 80 percent by weight. For example, the liquid nicotine formulationmay have a combined water, glycerine and propylene glycol content ofgreater than or equal to about 85 percent by weight.

The liquid nicotine formulation comprises one or more water-immisciblesolvents. The one or more water-immiscible solvents may advantageouslyhelp to dissolve and stabilise non-polar components of the liquidnicotine formulation.

The one or more water-immiscible solvents may reduce the hygroscopicityof an aerosol generated from the liquid nicotine formulation when usedin an aerosol-generating system. This may advantageously reduce orprevent increases in the particle or droplet size of the aerosol wheninhaled by a user as a result of adsorption of water in the respiratorytract.

When used in an aerosol-generating system, the liquid nicotineformulation generates an aerosol comprising dual-phase particles ordroplets comprising a water-miscible phase and a water-immiscible phase.This may advantageously reduce nicotine adsorption in the upper airwaysand enhance pulmonary nicotine delivery and retention. Without wishingto be bound by theory, the improvement in pulmonary nicotine deliveryand retention is believed to be due to coating or enveloping of thewater-miscible phase by the water immiscible phase. This is believed toreduce nicotine evaporation and adsorption in the upper airways.

Preferably, the liquid nicotine formulation has a water-immisciblesolvent content of greater than or equal to about 1 percent by weight.More preferably, the liquid nicotine formulation has a water-immisciblesolvent content of greater than or equal to about 2 percent by weight.For example, the liquid nicotine formulation may have a water-immisciblesolvent content of greater than or equal to about 4 percent by weight,greater than or equal to about 6 percent by weight or greater than orequal to about 8 percent by weight.

The liquid nicotine formulation may have a water-immiscible solventcontent of less than or equal to about 40 percent by weight.

Preferably, the liquid nicotine formulation has a water-immisciblesolvent content of less than or equal to about 35 percent by weight.More preferably, the liquid nicotine formulation has a water-immisciblesolvent content of less than or equal to about 30 percent by weight. Forexample, the liquid nicotine formulation may have a water-immisciblesolvent content of less than or equal to about 25 percent by weight,less than or equal to about 20 percent by weight or less than or equalto about 15 percent by weight.

The liquid nicotine formulation may have a water-immiscible solventcontent of between about 1 percent by weight and about 40 percent byweight. Preferably, the liquid nicotine formulation has awater-immiscible solvent content of between about 1 percent by weightand about 35 percent by weight. For example, the liquid nicotineformulation may have a water-immiscible solvent content of between about1 percent by weight and about 30 percent by weight, between about 1percent by weight and about 25 percent by weight, between about 1percent by weight and about 20 percent by weight or between about 1percent by weight and about 15 percent by weight.

The liquid nicotine formulation may have a water-immiscible solventcontent of between about 2 percent by weight and about 40 percent byweight. More preferably, the liquid nicotine formulation has awater-immiscible solvent content of between about 2 percent by weightand about 35 percent by weight. For example, the liquid nicotineformulation may have a water-immiscible solvent content of between about2 percent by weight and about 30 percent by weight, between about 2percent by weight and about 25 percent by weight, between about 2percent by weight and about 20 percent by weight or between about 2percent by weight and about 15 percent by weight.

The liquid nicotine formulation may have a water-immiscible solventcontent of between about 4 percent by weight and about 40 percent byweight or between about 4 percent by weight and about 35 percent byweight. For example, the liquid nicotine formulation may have awater-immiscible solvent content of between about 4 percent by weightand about 30 percent by weight, between about 4 percent by weight andabout 25 percent by weight, between about 4 percent by weight and about20 percent by weight or between about 4 percent by weight and about 15percent by weight.

The liquid nicotine formulation may have a water-immiscible solventcontent of between about 6 percent by weight and about 40 percent byweight or between about 6 percent by weight and about 35 percent byweight. For example, the liquid nicotine formulation may have awater-immiscible solvent content of between about 6 percent by weightand about 30 percent by weight, between about 6 percent by weight andabout 25 percent by weight, between about 6 percent by weight and about20 percent by weight or between about 6 percent by weight and about 15percent by weight.

The liquid nicotine formulation may have a water-immiscible solventcontent of between about 8 percent by weight and about 40 percent byweight or between about 8 percent by weight and about 35 percent byweight. For example, the liquid nicotine formulation may have awater-immiscible solvent content of between about 8 percent by weightand about 30 percent by weight, between about 8 percent by weight andabout 25 percent by weight, between about 8 percent by weight and about20 percent by weight or between about 8 percent by weight and about 15percent by weight.

Preferably, the one or more water-immiscible solvents comprise one ormore partially water-soluble solvents.

As used herein with reference to the first aspect of the invention, theterm “partially water-soluble solvent” describes a compound that isliquid at 20° C. and has a water solubility at 20° C. of between about20 mg/ml and about 100 mg/ml.

As used herein with reference to the second aspect of the invention, theterm “partially water-soluble solvent” describes a compound that isliquid at 20° C. and has a partition coefficient (log P) at 20° C. ofbetween about 0.05 and about 0.5.

The one or more partially water-soluble solvents may have a maximumcarbon chain length of less than or equal to 12. For example, the one ormore partially water-soluble solvents may have a maximum carbon chainlength of less than or equal to 10.

Suitable partially water-soluble solvents include, but are not limitedto, polysorbate 80, triethyl citrate and triacetin.

Preferably, the liquid nicotine formulation has a partiallywater-soluble solvent content of greater than or equal to about 0.5percent by weight. More preferably, the liquid nicotine formulation hasa partially water-soluble solvent content of greater than or equal toabout 1 percent by weight. For example, the liquid nicotine formulationmay have a partially water-soluble solvent content of greater than orequal to about 2 percent by weight, greater than or equal to about 4percent by weight, greater than or equal to about 6 percent by weight,greater than or equal to about 7 percent by weight or greater than orequal to about 8 percent by weight.

Preferably, the liquid nicotine formulation has a partiallywater-soluble solvent content of less than or equal to about 30 percentby weight. For example, the liquid nicotine formulation may have apartially water-soluble, water-immiscible solvent content of less thanor equal to about 25 percent by weight, less than or equal to about 20percent by weight or less than or equal to about 15 percent by weight.

Preferably, the liquid nicotine formulation has a partiallywater-soluble, water-immiscible solvent content of between about 0.5percent by weight and about 30 percent by weight. For example, theliquid nicotine formulation may have a partially water-soluble solventcontent of between about 0.5 percent by weight and about 25 percent byweight, between about 0.5 percent by weight and about 20 percent byweight or between about 0.5 percent by weight and about 15 percent byweight.

More preferably, the liquid nicotine formulation has a partiallywater-soluble solvent content of between about 1 percent by weight andabout 30 percent by weight. For example, the liquid nicotine formulationmay have a partially water-soluble solvent content of between about 1percent by weight and about 25 percent by weight, between about 1percent by weight and about 20 percent by weight or between about 1percent by weight and about 15 percent by weight.

The liquid nicotine formulation may have a partially water-solublesolvent content of between about 2 percent by weight and about 30percent by weight. For example, the liquid nicotine formulation may havea partially water-soluble solvent content of between about 2 percent byweight and about 25 percent by weight, between about 2 percent by weightand about 20 percent by weight or between about 2 percent by weight andabout 15 percent by weight.

The liquid nicotine formulation may have a partially water-solublesolvent content of between about 4 percent by weight and about 30percent by weight. For example, the liquid nicotine formulation may havea partially water-soluble solvent content of between about 4 percent byweight and about 25 percent by weight, between about 4 percent by weightand about 20 percent by weight or between about 4 percent by weight andabout 15 percent by weight.

The liquid nicotine formulation may have a partially water-solublesolvent content of between about 6 percent by weight and about 30percent by weight. For example, the liquid nicotine formulation may havea partially water-soluble solvent content of between about 6 percent byweight and about 25 percent by weight, between about 6 percent by weightand about 20 percent by weight or between about 6 percent by weight andabout 15 percent by weight.

The liquid nicotine formulation may have a partially water-solublesolvent content of between about 7 percent by weight and about 30percent by weight. For example, the liquid nicotine formulation may havea partially water-soluble solvent content of between about 7 percent byweight and about 25 percent by weight, between about 7 percent by weightand about 20 percent by weight or between about 7 percent by weight andabout 15 percent by weight.

The liquid nicotine formulation may have a partially water-solublesolvent content of between about 8 percent by weight and about 30percent by weight. For example, the liquid nicotine formulation may havea partially water-soluble solvent content of between about 8 percent byweight and about 25 percent by weight, between about 8 percent by weightand about 20 percent by weight or between about 8 percent by weight andabout 15 percent by weight.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be greater than or equal to about 0.75.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be at least about 0.75 times theweight percent nicotine content of the liquid nicotine formulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent nicotine content of the liquidnicotine formulation is greater than or equal to about 1. For example,the ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be greater than or equal to about 1.25, greater than orequal to about 1.5 or greater than or equal to about 1.75.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be less than or equal to about 20.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be less than or equal to 20 timesthe weight percent nicotine content of the liquid nicotine formulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent nicotine content of the liquidnicotine formulation is less than or equal to about 18. For example, theratio of the weight percent partially water-soluble solvent content tothe weight percent nicotine content of the liquid nicotine formulationmay be less than or equal to about 16, less than or equal to about 14 orless than or equal to about 12.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be between about 0.75 and about 20, between about 0.75and about 18, between about 0.75 and about 16, between about 0.75 andabout 14 or between about 0.75 and about 12.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent nicotine content of the liquidnicotine formulation is between about 1 and about 20, between about 1and about 18, between about 1 and about 16, between about 1 and about 14or between about 1 and about 12.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be between about 1.25 and about 20, between about 1.25and about 18, between about 1.25 and about 16, between about 1.25 andabout 14 or between about 1.25 and about 12.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be between about 1.5 and about 20, between about 1.5 andabout 18, between about 1.5 and about 16, between about 1.5 and about 14or between about 1.5 and about 12.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent nicotine content of the liquid nicotineformulation may be between about 1.75 and about 20, between about 1.75and about 18, between about 1.75 and about 16, between about 1.75 andabout 14 or between about 1.75 and about 12.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-miscible solvent content of the liquidnicotine formulation may be greater than or equal to about 0.06.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be at least about 0.06 times theweight percent water-miscible solvent content of the liquid nicotineformulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-miscible solvent content ofthe liquid nicotine formulation is greater than or equal to about 0.08.For example, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-miscible solvent content ofthe liquid nicotine formulation may be greater than or equal to about0.1, greater than or equal to about 0.12 or greater than or equal toabout 0.14.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-miscible solvent content of the liquidnicotine formulation may be less than or equal to about 1.2.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be less than or equal to about 1.2times the weight percent water-miscible solvent content of the liquidnicotine formulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-miscible solvent content ofthe liquid nicotine formulation is less than or equal to about 1. Forexample, the ratio of the weight percent partially water-soluble solventcontent to the weight percent water-miscible solvent content of theliquid nicotine formulation may be less than or equal to about 0.8, lessthan or equal to about 0.6 or less than or equal to about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-miscible solvent content of the liquidnicotine formulation may be between about 0.06 and about 1.2, betweenabout 0.06 and about 1, between about 0.06 and about 0.8, between about0.06 and about 0.6 or between about 0.06 and about 0.4.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-miscible solvent content ofthe liquid nicotine formulation is between about 0.08 and about 1.2,between about 0.08 and about 1, between about 0.08 and about 0.8,between about 0.08 and about 0.6 or between about 0.08 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-miscible solvent content of the liquidnicotine formulation may be between about 0.1 and about 1.2, betweenabout 0.1 and about 1, between about 0.1 and about 0.8, between about0.1 and about 0.6 or between about 0.1 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-miscible solvent content of the liquidnicotine formulation may be between about 0.12 and about 1.2, betweenabout 0.12 and about 1, between about 0.12 and about 0.8, between about0.1 and about 0.6 or between about 0.12 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-miscible solvent content of the liquidnicotine formulation may be between about 0.14 and about 1.2, betweenabout 0.14 and about 1, between about 0.14 and about 0.8, between about0.14 and about 0.6 or between about 0.14 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water content of the liquid nicotine formulationmay be greater than or equal to about 0.025.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be at least about 0.02 times theweight percent water content of the liquid nicotine formulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water content of the liquidnicotine formulation is greater than or equal to about 0.03. Forexample, the ratio of the weight percent partially water-soluble solventcontent to the weight percent water content of the liquid nicotineformulation may be greater than or equal to about 0.05, greater than orequal to about 0.075 or greater than or equal to about 0.1.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water content of the liquid nicotine formulationmay be less than or equal to about 5.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be less than or equal to about 5times the weight percent water content of the liquid nicotineformulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water content of the liquidnicotine formulation is less than or equal to about 1. For example, theratio of the weight percent partially water-soluble solvent content tothe weight percent water content of the liquid nicotine formulation maybe less than or equal to about 0.8, less than or equal to about 0.6 orless than or equal to about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water content of the liquid nicotine formulationmay be between about 0.02 and about 1.2, between about 0.02 and about 1,between about 0.02 and about 0.8, between about 0.02 and about 0.6 orbetween about 0.02 and about 0.4.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water content of the liquidnicotine formulation is between about 0.03 and about 1.2, between about0.03 and about 1, between about 0.03 and about 0.8, between about 0.03and about 0.6 or between about 0.03 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water content of the liquid nicotine formulationmay be between about 0.05 and about 1.2, between about 0.05 and about 1,between about 0.05 and about 0.8, between about 0.05 and about 0.6 orbetween about 0.05 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water content of the liquid nicotine formulationmay be between about 0.75 and about 1.2, between about 0.75 and about 1,between about 0.75 and about 0.8, between about 0.75 and about 0.6 orbetween about 0.75 and about 0.4.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water content of the liquid nicotine formulationmay be between about 0.1 and about 1.2, between about 0.1 and about 1,between about 0.1 and about 0.8, between about 0.1 and about 0.6 orbetween about 0.1 and about 0.4.

Preferably, the one or more water-immiscible solvents comprise one ormore water-insoluble solvents.

As used herein with reference to the first aspect of the invention, theterm “water-insoluble solvent” describes a compound that is liquid at20° C. and has a water solubility at 20° C. of less than or equal toabout 5 mg/ml.

As used herein with reference to the second aspect of the invention, theterm “water-insoluble solvent” describes a compound that is liquid at20° C. and has a partition coefficient (log P) at 20° C. of greater thanabout 5.

The one or more water-insoluble solvents may have a maximum carbon chainlength of less than or equal to 30. For example, the one or morewater-insoluble solvents may have a maximum carbon chain length of lessthan or equal to 20, less than or equal to 18, less than or equal to 16,less than or equal to 14 or less than or equal to 12.

Suitable water-insoluble solvents include, but are not limited to oleicacid and MIGLYOL® (mixture of decanoyl- and octanoyl glycerides).

Preferably, the liquid nicotine formulation has a water-insolublesolvent content of greater than or equal to about 0.5 percent by weight.More preferably, the liquid nicotine formulation has a water-insolublesolvent content of greater than or equal to about 1 percent by weight.For example, the liquid nicotine formulation may have a water-insolublesolvent content of greater than or equal to about 2 percent by weight,greater than or equal to about 3 percent by weight, greater than orequal to about 4 percent by weight or greater than or equal to about 6percent by weight.

The liquid nicotine formulation may have a water-insoluble solventcontent of less than or equal to about 30 percent by weight.

Preferably, the liquid nicotine formulation has a water-insolublesolvent content of less than or equal to about 25 percent by weight. Forexample, the liquid nicotine formulation may have a water-insolublesolvent content of less than or equal to about 20 percent by weight,less than or equal to about 15 percent by weight or less than or equalto about 10 percent by weight.

Preferably, the liquid nicotine formulation has a water-insolublesolvent content of between about 0.5 percent by weight and about 25percent by weight. For example, the liquid nicotine formulation may havea water-insoluble solvent content of between about 0.5 percent by weightand about 20 percent by weight, between about 0.5 percent by weight andabout 15 percent by weight or between about 0.5 percent by weight andabout 10 percent by weight.

More preferably, the liquid nicotine formulation has a water-insolublesolvent content of between about 1 percent by weight and about 25percent by weight. For example, the liquid nicotine formulation may havea water-insoluble solvent content of between about 1 percent by weightand about 20 percent by weight, between about 1 percent by weight andabout 15 percent by weight or between about 1 percent by weight andabout 10 percent by weight.

The liquid nicotine formulation may have a water-insoluble solventcontent of between about 2 percent by weight and about 25 percent byweight. For example, the liquid nicotine formulation may have awater-insoluble solvent content of between about 2 percent by weight andabout 20 percent by weight, between about 2 percent by weight and about15 percent by weight or between about 2 percent by weight and about 10percent by weight.

The liquid nicotine formulation may have a water-insoluble solventcontent of between about 3 percent by weight and about 25 percent byweight. For example, the liquid nicotine formulation may have awater-insoluble solvent content of between about 3 percent by weight andabout 20 percent by weight, between about 3 percent by weight and about15 percent by weight or between about 3 percent by weight and about 10percent by weight.

The liquid nicotine formulation may have a water-insoluble solventcontent of between about 4 percent by weight and about 25 percent byweight. For example, the liquid nicotine formulation may have awater-insoluble solvent content of between about 4 percent by weight andabout 20 percent by weight, between about 4 percent by weight and about15 percent by weight or between about 4 percent by weight and about 10percent by weight.

More preferably, the one or more water-immiscible solvents comprise oneor more partially water-soluble solvents and one or more water-insolublesolvents.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-insoluble solvent content of the liquidnicotine formulation may be greater than or equal to about 0.2.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be at least about 0.2 times theweight percent water-insoluble solvent content of the liquid nicotineformulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-insoluble solvent content ofthe liquid nicotine formulation is greater than or equal to about 0.4.For example, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-insoluble solvent content ofthe liquid nicotine formulation may be greater than or equal to about0.6, greater than or equal to about 0.8 or greater than or equal toabout 1.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-insoluble solvent content of the liquidnicotine formulation may be less than or equal to about 35.

That is, the weight percent partially water-soluble solvent content ofthe liquid nicotine formulation may be less than or equal to 35 timesthe weight percent water-insoluble solvent content of the liquidnicotine formulation.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-insoluble solvent content ofthe liquid nicotine formulation is less than or equal to about 30. Forexample, the ratio of the weight percent partially water-soluble solventcontent to the weight percent water-insoluble solvent content of theliquid nicotine formulation may be less than or equal to about 25, lessthan or equal to about 20 or less than or equal to about 15.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-insoluble solvent content of the liquidnicotine formulation may be between about 0.2 and about 35, betweenabout 0.2 and about 30, between about 0.2 and about 25, between about0.2 and about 20 or between about 0.2 and about 15.

Preferably, the ratio of the weight percent partially water-solublesolvent content to the weight percent water-insoluble solvent content ofthe liquid nicotine formulation is between about 0.4 and about 35,between about 0.4 and about 30, between about 0.4 and about 25, betweenabout 0.4 and about 20 or between about 0.4 and about 15.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-insoluble solvent content of the liquidnicotine formulation may be between about 0.6 and about 35, betweenabout 0.6 and about 30, between about 0.6 and about 25, between about0.6 and about 20 or between about 0.6 and about 15.

The ratio of the weight percent partially water-soluble solvent contentto the weight percent water-insoluble solvent content of the liquidnicotine formulation may be between about 0.8 and about 35, betweenabout 0.8 and about 30, between about 0.8 and about 25, between about0.8 and about 20 or between about 0.8 and about 15.

The liquid nicotine formulation comprises one or more water-solubleorganic acids. The one or more water-soluble organic acids mayadvantageously bind nicotine in the liquid nicotine formulation throughformation of one or nicotine salts.

The one or more nicotine salts may advantageously be dissolved andstabilised in the one or more water-miscible solvents. This mayadvantageously reduce nicotine adsorption in the upper airways andenhance pulmonary nicotine delivery and retention.

In embodiments where the liquid nicotine formulation comprises water andone or more water-miscible solvents, the one or more nicotine salts mayadvantageously be dissolved and stabilised in the water and one or morewater-miscible solvents.

Preferably, the liquid nicotine formulation comprises one or morewater-soluble carboxylic acids.

Suitable water-soluble carboxylic acids include, but are not limited to,acetic acid, citric acid, lactic acid, levulinic acid, malic acid,malonic acid and pyruvic acid.

More preferably, the liquid nicotine formulation comprises lactic acid.

Preferably, the liquid nicotine formulation has a water-soluble organicacid content of greater than or equal to about 2 percent by weight. Morepreferably, the liquid nicotine formulation has a water-soluble acidcontent of greater than or equal to about 3 percent by weight.

Preferably, the liquid nicotine formulation has a water-soluble organicacid content of less than or equal to about 8 percent by weight. Morepreferably, the liquid nicotine formulation has a water-soluble organicacid content of less than or equal to about 6 percent by weight.

Preferably, the liquid nicotine formulation has a water-soluble organicacid content of between about 2 percent by weight and about 8 percent byweight. For example, the liquid nicotine formulation may have awater-soluble organic acid content of between about 2 percent by weightand about 6 percent by weight.

More preferably, the liquid nicotine formulation has a water-solubleorganic acid content of between about 3 percent by weight and about 8percent by weight. For example, the liquid nicotine formulation may havea water-soluble organic acid content of between about 2 percent byweight and about 6 percent by weight.

The liquid nicotine formulation may be a substantially uncaffeinatedliquid nicotine formulation.

As used herein with reference to the invention, the term “substantiallyuncaffeinated liquid nicotine formulation” describes a liquid nicotineformulation having a caffeine content of less than 0.5 percent byweight. For example, the liquid nicotine formulation may have a caffeinecontent of less than about 0.4 percent by weight, less than about 0.3percent by weight or less than about 0.2 percent by weight.

The liquid nicotine formulation may be a substantially caffeine-freeliquid nicotine formulation.

As used herein with reference to the invention, the term “substantiallycaffeine-free liquid nicotine formulation” describes a liquid nicotineformulation having a caffeine content of less than about 0.1 percent byweight.

The liquid nicotine formulation may be a caffeine-free liquid nicotineformulation.

As used herein with reference to the invention, the term “caffeine-freeliquid nicotine formulation” describes a liquid nicotine formulationhaving a caffeine content of 0 percent by weight.

As used herein with reference to the invention, the term “caffeine”describes caffeine or a caffeine salt. When referring to a caffeinesalt, the amounts of caffeine recited herein are the amount of caffeinecation.

The liquid nicotine formulation may comprise one or more solidemulsifiers.

As used herein with reference to the invention, the term “solidemulsifier” describes an emulsifier that is solid at 20° C. Suitablesolid emulsifiers include, but are not limited to,1-Stearoyl-rac-glycerol, Kolliphor® P 188, sodium caseinate, sodiumdodecanoate and sodium docusate.

Preferably, the liquid nicotine formulation has a solid emulsifiercontent of less than or equal to about 8 percent by weight. Morepreferably, the liquid nicotine formulation has a solid emulsifiercontent of less than or equal to about 5 percent by weight.

The liquid nicotine formulation may comprise one or more flavourants.Suitable flavourants include, but are not limited to, menthol.

Preferably, the liquid nicotine formulation has a flavourant content ofless than or equal to about 4 percent by weight. More preferably, theliquid nicotine formulation has a flavourant content of less than orequal to about 3 percent by weight.

According to the invention there is also provided a cartridge for use inan aerosol-generating system, the cartridge containing a liquid nicotineformulation according to the invention.

The cartridge may comprise an atomiser configured to generate an aerosolfrom the liquid nicotine formulation.

A cartridge containing the liquid nicotine formulation and an atomiserconfigured to generate an aerosol from the liquid nicotine formulationmay be referred to as a “cartomiser”.

The atomiser may be a thermal atomiser.

As used herein with reference to the invention, the term “thermalatomiser” describes an atomiser that is configured to heat the liquidnicotine formulation to generate an aerosol.

The cartridge may comprise any suitable type of thermal atomiser.

The thermal atomiser may comprise a heater and a liquid transportelement configured to transport liquid nicotine formulation to theheater.

The liquid transport element may comprise a capillary wick. The heatermay comprise a heater coil.

The thermal atomiser may comprise an electric heater. For example, thethermal atomiser may comprise an electric heater comprising a resistiveheating element or an inductive heating element.

The atomiser may be a non-thermal atomiser.

As used herein with reference to the invention, the term “non-thermalatomiser” describes an atomiser that is configured to generate anaerosol from the liquid nicotine formulation by means other thanheating.

The cartridge may comprise any suitable type of non-thermal atomiser.

For example, the non-thermal atomiser may be an impinging jet atomiser,an ultrasonic atomiser or a vibrating mesh atomiser.

According to the invention there is further provided anaerosol-generating system comprising a liquid nicotine formulationaccording to the invention and an atomiser configured to generate anaerosol from the liquid nicotine formulation.

The atomiser may be a thermal atomiser.

The aerosol-generating system may comprise any suitable type of thermalatomiser.

The thermal atomiser may comprise a heater and a liquid transportelement configured to transport liquid nicotine formulation to theheater.

The liquid transport element may comprise a capillary wick. The heatermay comprise a heater coil.

The thermal atomiser may comprise an electric heater. For example, thethermal atomiser may comprise an electric heater comprising a resistiveheating element or an inductive heating element.

The atomiser may be a non-thermal atomiser.

The aerosol-generating system may comprise any suitable type ofnon-thermal atomiser.

For example, the non-thermal atomiser may be an impinging jet atomiser,an ultrasonic atomiser or a vibrating mesh atomiser.

The aerosol-generating system may comprise: a cartridge according to theinvention containing the liquid nicotine formulation; and anaerosol-generating device comprising a housing defining a device cavityconfigured to receive at least a portion of the cartridge.

The aerosol-generating system may comprise: a consumable cartridgeaccording to the invention containing the liquid nicotine formulation;and a reusable aerosol-generating device comprising a housing defining adevice cavity configured to receive at least a portion of the cartridge.

The aerosol-generating device may comprise a battery and controlelectronics.

The aerosol-generating system may comprise: a cartridge according to theinvention containing the liquid nicotine formulation and the atomiser;and an aerosol-generating device comprising a housing defining a devicecavity configured to receive at least a portion of the cartridge.

The aerosol-generating system may comprise: a cartridge according to theinvention containing the liquid nicotine formulation; and anaerosol-generating device comprising a housing defining a device cavityconfigured to receive at least a portion of the cartridge and theatomiser.

For the avoidance of doubt, features described above in relation to oneaspect of the invention may also be applicable to other aspects of theinvention. In particular, features described above in relation to theliquid nicotine formulation of the invention may also relate, whereappropriate, to the cartridge of the invention and theaerosol-generating system of the invention. Similarly, featuresdescribed above in relation to the cartridge of the invention may alsorelate, where appropriate, to the aerosol-generating system of theinvention, and vice versa.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the following examples:

EXAMPLES 1-3

Three liquid nicotine formulations according to the invention (Examples1, 2 and 3) were prepared having the compositions shown in Tables 2, 3and 4.

TABLE 2 Example 1 Component % by weight Nicotine 2 Water 31 VegetableGlycerine water-miscible solvent 31 Triethyl Citrate water-immisciblesolvent 30 Polysorbate 80 1 Lactic Acid water-soluble organic acid 3Flavourant 2

TABLE 3 Example 2 Component % by weight Nicotine 2 Water 27 VegetableGlycerine water-miscible solvent 30 Propylene Glycol 20 Triethyl Citratewater-immiscible solvent 5 Polysorbate 80 3 Miglyol ® 5 Lactic Acidwater-soluble organic acid 6 Flavourant 2

TABLE 4 Example 3 Component % by weight Nicotine 5 Water 7 VegetableGlycerine water-miscible solvent 24 Propylene Glycol 24 Polysorbate 80water-immiscible solvent 30 Miglyol ® 1 Lactic Acid water-solubleorganic acid 7 Flavourant 2

EXAMPLES A-F

Six liquid nicotine formulations according to the invention (Examples A,B, C, D, E and F) were prepared having the compositions shown in Table5. For comparison, two liquid nicotine formulations not according to theinvention (Examples G and H) were also prepared having the compositionsshown in Table 5.

The liquid nicotine formulations of Examples A-H were each loaded into acartridge for a Solaris e-cigarette. The nicotine retention of theaerosols generated when using the cartridges in a Solaris e-cigarettewere measured using denuder tube technology essentially as described inSeeman, J. I.; Lipowicz, P. J.; Piade, J.-J.; Poget, L.; Sanders, E. B.;Snyder, J. P.; Trowbridge, C. G., On the Deposition of Volatiles andSemivolatiles from Cigarette Smoke Aerosols: Relative Rates of Transferof Nicotine and Ammonia from Particles to the Gas Phase. ChemicalResearch in Toxicology 2004, 17, 1020-1037, with the followingmodifications: the aerosol was pulled and not pushed; 55 ml puffs wereused rather than 35 ml puffs; the denuder used was a 30 m Tygon® tube;the difference in nicotine yield was measured by comparing what wascollected from the product onto a Cambridge pad with and without theTygon® tube rather than by measuring what was collected by the denuderand by the Cambridge pad positioned after the denuder. For comparison,the nicotine retention of the smoke generated when combusting aconventional cigarette (Example I) was also measured. The results areshown in Table 5.

As shown in Table 5, the aerosols generated from the liquid nicotineformulations according to the invention (Examples A-F) provide nicotineretentions of greater than 40 percent. By contrast, the aerosolsgenerated from the liquid formulations not according to the invention(Examples G and H) provide lower nicotine retentions of less than 30percent.

The nicotine retention properties of the aerosols generated from theliquid nicotine formulations according to the invention (Examples A-F)are at least 13.5 times greater than the liquid formulation notaccording to the invention that does not comprise either awater-immiscible solvent having a water solubility at 20° C. of lessthan or equal to about 100 mg/ml or a water-soluble organic acid(Example G).

The nicotine retention properties of the aerosols generated from theliquid nicotine formulations according to the invention (Examples A-F)are at least about 1.5 times greater than the liquid formulation notaccording to the invention that does not comprise a water-immisciblesolvent having a water solubility at 20° C. of less than or equal toabout 100 mg/ml (Example H).

The nicotine retention properties of the aerosols generated from theliquid nicotine formulations according to the invention (Examples A-F),which comprise both a water-immiscible solvent having a water solubilityat 20° C. of less than or equal to about 100 mg/ml and a water-solubleorganic acid, are similar to the nicotine retention properties of thesmoke generated from the conventional cigarette (Example I).

TABLE 5 Example A B C D E F G H I Nicotine (% by weight) 2.7 2.7 2.7 2.72.7 2.7 5 5 — Water (% by weight) 80 60 40 80 60 40 20 20 — VegetableGlycerine (% by weight) water-miscible 8.7 25 45 8.7 25 45 37.5 34.7 —Propylene Glycol (% by weight) solvent 1.5 4.2 4.2 1.5 4.2 4.2 37.5 34.7— Triacetin (% by weight) water-immiscible 0.9 2 2 0.9 2 2 0 0 —Triethyl Citrate (% by weight) solvent 2 2 2 2 2 2 0 0 — Lactic Acid (%by weight) water-soluble 4.3 4.3 4.3 0 0 0 0 5.6 — Levulinic Acid (% byweight) organic acid 0 0 0 4.3 4.3 4.3 0 0 — Nicotine Retention (%) 73.762.9 50.7 61.0 53.5 41.6 1-3% 25-28% 36-39%

1.-15. (canceled)
 16. A liquid nicotine formulation for anaerosol-generating system, the liquid nicotine formulation comprising:one or more water-miscible solvents; one or more water-immisciblesolvents having a water solubility at 20° C. of less than or equal toabout 100 mg/ml; and one or more water-soluble organic acids, whereinthe liquid nicotine formulation has a water-immiscible solvent contentof greater than or equal to about 2 percent by weight.
 17. A liquidnicotine formulation according to claim 16, wherein the one or morewater-immiscible solvents comprise one or more partially water-solublesolvents having a water solubility at 20° C. of between about 20 mg/mland about 100 mg/ml.
 18. A liquid nicotine formulation according toclaim 16, wherein the one or more water-immiscible solvents comprise oneor more water-insoluble solvents having a water solubility at 20° C. ofless than or equal to about 5 mg/ml
 19. A liquid nicotine formulationfor an aerosol-generating system, the liquid nicotine formulationcomprising: one or more water-miscible solvents; one or morewater-immiscible solvents having a partition coefficient (log P) at 20°C. of greater than or equal to about 0.05; and one or more water-solubleorganic acids, wherein the liquid nicotine formulation has awater-immiscible solvent content of greater than or equal to about 2percent by weight.
 20. The liquid nicotine formulation according toclaim 19, wherein the one or more water-immiscible solvents comprise oneor more partially water-soluble solvents having a partition coefficient(log P) at 20° C. of between about 0.05 and about 0.5.
 21. The liquidnicotine formulation according to claim 19, wherein the one or morewater-immiscible solvents comprise one or more water-insoluble solventshaving a partition coefficient (log P) at 20° C. of greater than about5.
 22. The liquid nicotine formulation according to claim 16, whereinthe liquid nicotine formulation comprises water.
 23. The liquid nicotineformulation according to claim 16, wherein the one or morewater-miscible solvents are one or more water-miscible polyhydricalcohols.
 24. The liquid nicotine formulation according to claim 16,wherein the one or more water-miscible solvents are one or morewater-miscible polyhydric alcohols selected from the group consisting of1,3-butanediol, glycerine, propylene glycol, and triethylene glycol. 25.The liquid nicotine formulation according to claim 16, wherein the oneor more water-immiscible solvents are selected from the group consistingof oleic acid, a mixture of decanoyl- and octanoyl glycerides,triacetin, and triethyl citrate.
 26. The liquid nicotine formulationaccording to claim 16, wherein the liquid nicotine formulation has awater-soluble organic acid content of greater than or equal to about 2percent by weight.
 27. The liquid nicotine formulation according toclaim 16, wherein the one or more water-soluble organic acids areselected from the group consisting of acetic acid, lactic acid,levulinic acid, and pyruvic acid.
 28. A cartridge for anaerosol-generating system, the cartridge containing a liquid nicotineformulation according to claim
 16. 29. The cartridge according to claim28, further comprising an atomiser configured to generate an aerosolfrom the liquid nicotine formulation.
 30. An aerosol-generating system,comprising: a liquid nicotine formulation according to claim 16; and anatomiser configured to generate an aerosol from the liquid nicotineformulation.